Histology Subtype


**Note 1:** This SSDI is effective for diagnosis years 2023+. + For cases diagnosed 2018-2022, leave this SSDI blank **Note 2:** Use the Solid Tumor Rules to determine histology prior to coding this SSDI. **Note 3:** Histology 8480/2 or 8480/3 have multiple definitions that are collected in this histology. This data item is used to further identify specific subtypes for histology code 8480/2 or 8480/3. *Examples:* 1. Appendix: Disseminated peritoneal adenomucinous/low grade mucinous carcinoma peritonei. Final diagnosis: Low grade appendiceal mucinous neoplasm + Code 1: This is a low grade mucinous (appendiceal) carcinoma (8480/3), which is LAMN. The peritoneal adenomucinous/low grade mucinous carcinoma peritonei is describing metastatic disease and not the histology 2. Appendix: Low grade (well diff) appendiceal adenocarcinoma + Code 0: This is an adenocarcinoma (8140/3), the low grade (well diff) is describing the grade and not the histology 3. Appendix, appendectomy: Low grade appendiceal mucinous neoplasm (LAMN) with focal high grade mucinous neoplasm. + Code 1: Based on the Solid Tumor Rules, the “focal” would be ignored and this would be a LAMN. 4. Appendectomy: Mucinous adenocarcinoma of the appendix + Code 3: Mucinous adenocarcinoma is the preferred terminology for histology code 8480/3. Since there is no mention of “low grade” or “high grade”, this would not be LAMN or HAMN 5. Appendix: Mucinous (colloid) adenocarcinoma + Code 3: Colloid adenocarcinoma is an alternate name for 8480/3


NAACCR #3960


SSDI 2023–
Code Description
0 Histology is NOT 8480
1 Low-grade appendiceal mucinous neoplasm LAMN
2 High-grade appendiceal mucinous neoplasm HAMN
3 Mucinous Adenocarcinoma/carcinoma Mucus Adenocarcinoma/carcinoma Mucoid adenocarcinoma/carcinoma Colloid adenocarcinoma/carcinoma
4 Other terminology coded to 8480
<BLANK> NA-Diagnosis year is prior to 2023